HVOF Coating and Characterization
HVOF Coating is one of the thermal barrier coatings to protect surfaces from high temperature, corrosion, and erosion environments. Coating characteristics including thickness, metallurgy, elemental composition, and morphology play an important role in pr
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HVOF Coating and Characterization
Abstract HVOF Coating is one of the thermal barrier coatings to protect surfaces from high temperature, corrosion, and erosion environments. Coating characteristics including thickness, metallurgy, elemental composition, and morphology play an important role in practical applications. In this chapter, a brief description of HVOF coating process and coating characteristics is presented. The practical applications of HVOF coating and coating properties are also included in detail. Keywords HVOF coating properties
Microstructure
Morphology
Mechanical
3.1 Single Layer HVOF Coating and Characterization High Velocity Oxy-Fuel (HVOF) coatings find wide application in industry. HVOF process protective coating of metallic surface from the harsh environment such as high temperature, corrosion and wear environments. HVOF process is involved in thermal spraying of powder onto the surface through which the coating is resulted. The mechanical anchoring is the only process to bond the coating to the base material; consequently, a care is taken to improve the bonding strength between the coating and the base material during the HVOF process. The powders with carbide content are favorable for wear applications and nickel base powders are used for the corrosion protection. In the case of the wear applications, carbide and molybdenum base alloys are demanding. The results and discussions are classified according to the mechanical tests carried out in the present work. Therefore, the discussions of the findings are given under the appropriate headings in line with the previous studies [1–4].
B. S. Yilbas et al., Flexural Testing of Weld Site and HVOF Coating Characteristics, Materials Forming, Machining and Tribology, DOI: 10.1007/978-3-642-54977-9_3, Springer-Verlag Berlin Heidelberg 2014
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3 HVOF Coating and Characterization
Fig. 3.1 Load and displacement characteristics of the workpiece after threepoint bend tests [1]
3.1.1 The Point Bending Tests The results presented for three-point bending tests cover HVOF coating of AMDRY 9954 powders on Ti-6Al-4V alloy. The some of the HVOF coated surfaces are subjected to the heat treatment prior to the tests to resemble the gas turbine applications. The data obtained from the finite element analysis are also provided in the discussions in line with the previous study [5]. The elastic-plastic behavior of the workpiece with coating and without coating as well as with heat treatment is demonstrated in Fig. 3.1. The data for three-point bend tests are obtained under the constant strain rate bending. As-received uncoated and heat treated uncoated workpieces show similar elastic-plastic behavior while coated workpieces behaves slightly different in such a way that the formation of the plastic region takes place at low load levels for heat treated coated samples for the same flexural displacement. This indicates that heat treatment has an effect on the coating, since the heat treated uncoated and as-received uncoated workpieces behave s
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